Saturn and its rings shine in an image captured by the Hubble Space Telescope and released by NASA and the European Space Agency on Thursday. The image, taken on June 20, also shows four of Saturn's moons: Enceladus, Mimas, Janus and Tethys.

Studies of the Great Lakes and elsewhere show the vast reach of microplastics, which reach the oceans, rivers, streams and lakes through wastewater treatment facilities, writes Sherri Mason. "The plastic we use ultimately comes back to us in the food we eat and the water we drink," she writes.

Osteocalcin, a hormone produced by bones, may be what activates the fight-or-flight stress reaction in the brain rather than adrenaline, according to findings published in Cell Metabolism. "We hypothesize that bones may have been invented by evolution as a tool to escape danger, when animals left the sea to go to the land," says study author Gerard Karsenty.

Rats have been taught to play hide-and-seek with researchers, and the scientists say the rodents are not only good at it, but they seem to enjoy it, according to findings published in Science. The findings have given researchers clues about the rats' cognitive abilities and the ways they participate in play.

Investigators funded in part by the Department of Defense and the Army Research Office identified 27 blood markers that can be used along with heart rate to screen for post-traumatic stress disorder, according to a study published in Molecular Psychiatry. Military personnel may be reluctant to disclose PTSD symptoms, and population-based screening could help lift the stigma and ensure those who need treatment get it, says senior study author Charles Marmar.

A study in JAMA Psychiatry showed that 12- to 15-year-olds who spent more than six hours on social media daily had a threefold higher likelihood of developing internalizing mental health problems, such as depression, as well as a fourfold increase in odds of developing both internalizing and externalizing issues, such as bullying, compared with those who used no social media. Shorter duration of social media use was also associated with increased risk, but the association between social media use and externalizing behaviors alone was inconsistent.

The University of Wisconsin-Madison School of Veterinary Medicine received a $3 million, five-year grant from the NIH to fund One Health fellowships at 15 veterinary colleges, and one of the goals is to raise awareness of veterinary medicine among physicians. Early-career veterinary faculty will collaborate with other researchers studying similar diseases in humans such as skin allergies, osteoarthritis, cancer-related pain and epilepsy.

Environmental Protection Agency Administrator Andrew Wheeler on Tuesday ordered the agency to reduce funding for animal testing by 30% by 2025 and to eliminate it by 2035. Alternative testing options "have the potential to save hundreds of animals while providing more accurate information on chemical hazards, exposures and risks," says the American Chemistry Council.

Sigma Xi's Nobel Prize prediction contest, October Madness, is back! The competition collects nominations from the public and then runs voting to advance researchers in a sports-style bracket. Who do you think might accept this year's Nobel Prizes in chemistry, physics, physiology or medicine, or the Sveriges Riksbank Prize in Economic Sciences?

October 1 is the next deadline for undergraduate and graduate students to apply for Sigma Xi research grants. Michael Donovan used his Sigma Xi grant to collect data from the fossil plant collection at the Museo Paleontologico Egidio Feruglio in Trelew, Argentina.